Day 4-8 Severe Weather Outlook Issued on Aug 8, 2020
Updated: Sat Aug 8 08:07:03 UTC 2020
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 5 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 6 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 7 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 8 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4
Tue, Aug 11, 2020 - Wed, Aug 12, 2020
D7
Fri, Aug 14, 2020 - Sat, Aug 15, 2020
D5
Wed, Aug 12, 2020 - Thu, Aug 13, 2020
D8
Sat, Aug 15, 2020 - Sun, Aug 16, 2020
D6
Thu, Aug 13, 2020 - Fri, Aug 14, 2020
(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 080805
SPC AC 080805
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 AM CDT Sat Aug 08 2020
Valid 111200Z - 161200Z
...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
The medium-range models including the ECMWF, GFS, UKMET and Canadian
move a low-amplitude upper-level ridge across the northern high
Plains on Tuesday. The models suggest that severe thunderstorms will
be possible ahead of the ridge in parts of the eastern Dakotas and
Minnesota Tuesday afternoon and evening. However, the upper-level
ridge and lack of large-scale ascent could limit convective
coverage.
On Wednesday, the models move the upper-level ridge eastward across
the northern Plains and maintain a corridor of moderate to strong
instability in the eastern Dakotas. Thunderstorm development may
again be isolated Wednesday afternoon and evening but if convection
can initiate along the instability corridor, a localized severe
threat will be possible.
...Thursday/Day 6 to Saturday/Day 8...
On Thursday, the models are in general agreement that an upper-level
trough will move across the northwestern states as west-southwest
mid-level flow becomes established in the northern Plains. Strong to
severe thunderstorms will be possible Thursday afternoon and evening
in parts of eastern North Dakota and northwestern Minnesota along
the northwestern edge of a moist airmass. But convective coverage
again is problematic due to uncertainties concerning the timing of
the trough to the west.
The model solutions diverge on Friday and Saturday especially at
mid-levels. The models are in a bit better agreement at low-levels
with a moist and unstable airmass in eastern Nebraska and
southeastern South Dakota. If this where to pan out, isolated
thunderstorms would be possible along the instability axis both
afternoons on Friday and Saturday.
Overall, predictability remains too low and forecast convective
coverage appears too isolated throughout the Day 4 to 8 period for
an outlook area.
..Broyles.. 08/08/2020
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